Determining if a given cancer tumor is slow-growing or aggressive is important when choosing the right treatment. MRI scans can help doctors identify the location of a tumor, but do not provide much further information.

Researchers at Case Western University in Ohio modified a commercially available MRI contrast agent called tri-gadolinium nitride metallofullerene by attaching a peptide named ZD2 to its exterior. The peptide specifically sticks to the protein extradomain-B fibronectin, which is found in high concentrations around aggressive tumors in a number of cancers.

In mice with different types of breast cancer, the new contrast agent lit up clearly around all tumors, but was particularly prominent around the more aggressive tumors.

The new contrast agent is safer and more efficient than traditional agents, requiring a smaller dose and easily flushing from the body without accumulating in tissues, the researchers write.

Their next steps are reducing the cost of producing the agent and testing it in human patients.